The invention relates to a hydraulic camshaft adjuster for an internal combustion engine with a camshaft including a control valve having a control piston axially movably disposed in a valve housing for controlling the admission of hydraulic fluid to, and the release thereof from, a device for adjusting the angular position of the camshaft relative to the crankshaft of the engine.
For lowering the fuel consumption and the raw emissions of an engine and for increasing the engine power and engine torque gasoline engines are often provided with camshaft adjusters. The camshaft adjusters adjust the angular position of the camshaft relative to the crankshaft of the engine. Today, mostly hydraulic blade controllers with hydraulic operating chambers are used. The angular adjustment is performed by the controlled supply of oil from the engine oil circuit to the operating chambers of the blade controllers. The oil supply and the release of the oil is controlled by a control valve which is electromagnetically operated.
DE 198 17 319 A1 discloses a hydraulic camshaft adjuster for an internal combustion engine which includes a control valve with pressure medium flow control passages. By means of the control valve, an adjuster unit for the angular position adjustment of a camshaft can be controlled wherein the adjuster unit includes an inner body which is mounted to the camshaft for rotation therewith and an outer body which is rotatable relative to the camshaft and which is operatively connected to the crankshaft of the engine so as to be driven thereby. The control valve includes a control piston which is axially movably supported in a cylindrical cavity of a central clamping bolt by which the inner body is mounted axially to the camshaft. Pressurized fluid flow passages are provided in the camshaft and in the inner body of the camshaft adjuster which are difficult to machine into the camshaft and the control valve body so that the arrangement is difficult and expensive to manufacture.
It is the object of the present invention to provide a hydraulic camshaft adjuster with hydraulic fluid passages which are relatively easy to manufacture and wherein the arrangement at the same time is relatively small and lightweight.